The present invention relates to the control of a fuel injected internal combustion engine, and more particularly to a method of deactivating selected fuel injectors of the engine for the purpose of improving engine idle stability.
High performance internal combustion engines frequently exhibit stability problems when operating at or near idle speeds with little or no load. Traditional methods of improving stability under such conditions include controlling the intake airflow or spark timing. A potentially more attractive method of improving stability involves selective deactivation of certain fuel injectors during idle. This method improves stability by effectively increasing the load on the remaining engine cylinders, and offers the additional advantages of reducing fuel consumption and exhaust gas emissions. However, deactivating fuel injectors tends to be difficult to implement in a way that is not perceived by the vehicle occupants. Accordingly, what is needed is an improved method of carrying out a fuel injector deactivation idle stability control.
The present invention is directed to an improved idle stability control for a fuel injected internal combustion engine, wherein selected fuel injectors are deactivated after specified idle conditions have been met for a predetermined period of time, and thereafter until the conditions are no longer met, and wherein the engine spark timing is temporarily modified on each transition to and from the control to reduce operator perception of the injector deactivation and reactivation. Additionally, the injector deactivation pattern is periodically adjusted following an overlap period during which all of the injectors are enabled.